


I can't help it.

by SXH1417



Category: Undertale (Video Game)
Genre: Accidental Voyeurism, Masturbation, Mating Cycles/In Heat, One-Sided Attraction, Pining, Sibling Incest, Underfell Papyrus (Undertale), Underfell Sans (Undertale)
Language: English
Status: In-Progress
Published: 2019-11-04
Updated: 2020-03-13
Packaged: 2021-01-23 04:09:20
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 4
Words: 9,099
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21313948
Author URL: https://archiveofourown.org/users/SXH1417/pseuds/SXH1417
Summary: A kind of Creep series I am working on. This is all about situations and one-shots of the skele boys being creepy about their attractions.
Relationships: Papyrus/Sans (Undertale)
Comments: 11
Kudos: 119





	1. Fellcest with Creep Sans

**Author's Note:**

> I know it's been a while since I posted anything, but here please have this. I hope you guys enjoy

Sans felt like such a fucking pervert. Boss was making dinner again. His armor had long since been shed and traded for shorts and a tank top and Sans couldn't rip his eyelights away from the bones exposed. A pungent smell of spices permeated the house.

The smell obviously wasn't just caused by the lasagna. Sans could tell that Boss's heat was coming up. Surface or not, they were still very much affected by such things. Safety only seemed to make such heats more frequent. A fact that was driving Sans crazy. In the underground, Sans only had to smell it maybe one every three months. Now he was smelling it every month.

Boss was visibly sweating, the only sign that he was affected by such trivial biological functions. God, he was so cool...

_He was so pretty_

Sans bit out off the groan that tried to make it's way out of him. It came out as a grunt. The sound instantly caught Papyrus's attention. He managed to tear his eyes away from his brother's ass before Paps could catch him looking. He turned them to the TV that was showing some stupid sitcom that drove Paps up the wall most days. Sans loved the show but he couldn't give a single shit about it right now.

"What's wrong with you?" Boss snapped.

"nothin'. what's tomato with you?" He shot back with a shark-like grin.

Boss let out an exasperated groan but didn't persue the matter. A testament to how bad he felt. He prolly didn't even feel like cooking. Sans felt a small pang of guily. He should be the onr cooking. His brother deserved a break from it.

It would be so nice to take his place. Let Paps lay on the couch while he made some shitty food for them. Oh... oh it would be so good to see him show some sort of vulnerability. Only Boss could be a flushed, sweaty mess and still look completely powerful.

Enough of that thinking.

He pinched his pubic symphysis mercilessly. The pain evaporated any magic that tried to form. The glow in his shorts dispersed just in time for Boss to finish cooking.

"Dinner's ready," he said stiffly. Sans made sure to take his time in peeling himself off the couch. He grinned at the impatient and annoyed look his brother shot him as he slowly waltzed into the kitchen to the table. He flopped into Boss's chair just to annoy him.

<strike> _Just to have Boss pick him up and move him. _ </strike>

Surprisingly, Paps just shook his head and took Sans's usual seat. Sans eyed him critically. Boss pointedly avoided it as he shoved a plate towards him. And didn't something in his just feel so smug and satisfied about that.

"Just fucking eat, jackass," he grumbled.

Still side-eyeing his brother, Sans did. He wolfed down the meal in his usual manner. Boss scowled at his completely normal behavior.

"Barbarian," he accused.

"not completely," Sans said idly as he licked his teeth. "if i were a complete barbarian, i would have already carried you off to the bedroom."

Boss stiffened instantly. He shot a glare over to Sans, who met his eye-lights with an uneasy shit-eating grin and wink. Better to play it off. Please take it as a joke. Don't think that Sans was serious. Please.

"Jackass," Paps finally huffed. "Next time you go into heat, I don't want to hear you bitch one bit."

"Yeah, yeah," Sans chuckled as he went back to licking his plate clean and then going for seconds. The tension in his soul eased at Papyrus's dismissal. "Just go take a shower, Boss. yer stinking up the house."

Boss snarled and stood up from his seat. His patience was clearly gone as he took his plate upstairs.

"Go fuck yourself with a rusted spoon."

Sans smirked. He had a comeback ready, but bit his tongue as Boss poked his head back into the kitchen to growl.

"And since it bothers you so fucking much, _you_ get to do the laundry tonight."

Sans froze then regained enough of his head to snarl and hiss at his brother. Boss may be the boss but like hell was he going to wash Boss's stinking clothes or his own.

He childishly stuck his tongue out at the spot Boss previously occupied. Nonetheless, he went to put his plate in the sink. Despite the shit he put his brother through, he went ahead and started gathering clothes. Only Papyrus's though. He still wasn't washing his own. Boss could suck it.

His reasoning for actually doing what he was told, even half-assed, was because he knew Paps felt like shit. He gathered up the clothes from the basket in the bathroom first.

Apparently, Paps did take a shower after all. The clothes he had been wearing were in there. And as soon as Sans picked them up, he realized he fucked up.

Papyrus's stench was all over them. The heat scent was absolutely covering the clothes in his hands. Sans dropped them instantly like it burned to the touch. But, the smell clung to his hand. It was so strong. It was making his salivate.

Before he could stop himself, he was pressing his hand to his nasal aperture. He took a long whiff of it, taking in the smell and all the pheremones. His magic came back with a vengence, clouding his inlet while the smell clouded his skull.

His breath sped up. His eyelights dilated. Sinful images popped into his skull as he dug through the clothes to find that one piece... when he found it - Papyrus's boxers - he pressed them to his nose and shuddered. It was the strongest here.

His boxers were soaked in scent and magic. Sans couldn't get a hold of himself as he rubbed his face against it and licked the soaked patch. The taste had his magic forming instantly. His cock was hard and weeping already.

Want Need. _Mate_...

He needed to cum. He needed it now. He shoved his shorts down just enough to release his cock. Still pressing his face into those boxers he began to stroke himself fast and rough.

He didn't hold back his groans. His mind was lost to that scent.

"Uh... oh yeah... fuck... uh..." Words and sounds spilled out his mouth without his consent. The sounds of bone on magic quickly changed to wet, sloppy sounds. His cock constantly leaked with pre as he fucked his own hand.

Images of Papyrus filled his head. His pretty bones, chipped with so many fights that proved how strong he was, splayed out below him. Begging. Needy. Wanting his big bro to help him. Needing his cock to scratch that itch he just couldn't on his own. Wanting his big bro to mark him up. Show everyone just who he belonged to.

Sans growled in frustration. He wasn't getting enough friction from his hand. He snatched that tank top Pap had been wearing before. He wrapped it around his cock and started stroking again. As the burn of a little too much friction hit him, he groaned. He loved it.

"that's better..." he rumbled, half-growl, half-purr.

Papyrus would feel so much better than this though. His pretty magic would feel perfect around hin, no matter what he formed. He would moan and cry for Sans to take him, claim him, _ruin_ him.

Sans snarled as he came into the tank top suddenly. His bones rattled from the intensity. Drool had slipped down both sides of his mouth, making him looked like a starved man. His eyelights were dangerous. He wasn't done. Not by a long shot.

He started stroking his cock again, his cum slicking up the shirt and easing the burn. All he could think about was his brother under him.

* * *

Papyrus backed away from the bathroom door very slowly. He had covered his mouth to prevent an noise from escaping, even though he went mute from the shock.

He had just watched his brother's mental state disintegrate like cotton candy in water. He fought back the arousal that his brother's feral actions had started. If he was smelled now, his brother might actually attack him.

He crept back into his room and quietly shut the door behind him. He locked it for good measure. He stuffed blankets under the bottom and at the top of the door to keep his scent from escaping. He pulled out the box of toys he kept hidden under a false bottom of his desk drawer.

He needed to deal with this heat quickly and hope he could look his brother in the eye when it was done.


	2. Swapcest

**Summary for the Chapter:**

> Sans really didn't deserve Papyrus's trust.

**Notes for the Chapter:**

> WARNING: This chapter contains Non-Consensual Sex. Papyrus is drugged and is unable to give consent.
> 
> Content warnings: Rape/Non-Con, Incest, Drugged Sex, Aphrodisiacs, Creep Blue, Older Brother Blue, Fingering, Vaginal Sex 
> 
> I finally got around to finishing this chapter. I actually started this one before Chapter 1. Anyway, I hope you guys enjoy this chapter!

Sans loved his brother. Obviously. There was never a fucking question about it. He made it quite obvious to everyone.

But, his brother seriously got on his nerves from time to time. He was lazy and a slob on occasion. He barely went to work, he got drunk at the bar, and he smoked those fucking deathsticks. He completely ignored his older brother's advice against such activities.

As he watched his brother stumble in the door yet again, he felt his eyesocket twitch. Papyrus tripped and fell agsinst the couch. Any attempt to get up was met with only him slumped on the floor.

"S... Saaaannnnsssssss..." Papyrus slurred. Sans ignored it for a minute or two, taking his time in finishing off his cup of coffee. "SAaAaannnnssss..."

Sans let out a loud sigh. He downed the rest of his coffee and got up. Rinsing his cup out, he then set it aside to dry. Only then did he deign to walk into the living room to check on Papyrus. One look told Sans that his brother was fine, physically speaking. But Sans balked nonetheless.

Papyrus was sprawled completely on the floor. He somehow had managed to wiggle out of his hoodie. His shorts were shimmied down his hips, nearly exposing his pubic symphysis. Sans flushed a little looking at the sight. Papyrus was squirming around on the ground. His bones were flushed and his soul was shining brightly through his black tanktop.

"Papyrus... What the actual fuck are you doing?" Sans asked. If his brother was appalled at all by language, he didn't show it. All the did was squirm and bare his throat. He wasn't in heat, that much was certain. He lacked the smell and the magical pull for a mate.

Not that Blue ever needed those to be attracted to him. Papyrus was sinfully gorgeous, coupled by the downright lewd sounds falling from his teeth, he was fucking irresistable.

"Sss..... Saaaannnnssss.... hoooooot..." Papyrus moaned, wiggling some more. His shirt rode up more but got caught on Stretch's sternum but showed Sans a hell of a lot of lumbar vertebrae.

Sans fought to keep his focus on his brother's face instead of those bones. In his peripheral vision, he could see orange magic gathering down low. The hazed eyelights tipped him off that his brother was not playing around or pulling a prank. This was serious.

He knelt down next to his brother and hovered his hand over his brother's bones, careful not to touch him. He could feel the warmth radiating off his bones and his magic attempting to reach for him, to cool him down. Sans had only witnessed this once before. It had been a few weeks ago at a training workshop in the capital. He'd seen this reaction from a new drug that hit the streets.

The drug acted like an aphrodisiac of sorts. It sent a person into a pseudo-heat that became harmful if the person didn't have a partner. It wasn't high on the guard's list of priorities. In fact, it wasn't really a problem to anyone.

The exception being low HP monsters.

If Sans had taken the drug, he would have been fine without a partner. He had plenty of HP to spare. His brother didn't.

He hadn't had to worry about it until now...

He had told Papyrus about this drug already, knowing that his brother would steer clear. While Papyrus did stupid things often, they never ever affected his HP. He was smarter than that. This was a fact that made Sans seethe.

It meant that someone had to have slipped it to Papyrus.

Sans took a few calming breaths, although it didn't remove the frown from his face. This was fine. Papyrus was going to be fine. The guard had given them a medical kit and instructions of how to use it if this situation ever occurred.

"Don't worry, Papy. I'll fix it. You'll feel better in no time," Sans assured as he got up. It pained him to rip himself away. The baser part of his mind was telling him to stay and help Papyrus in a different way. 

As he began to pull away a hand reached out to him and pulled him back down. He stumbled a little, falling to his knees over his brother.

"Noooo.... pleaaaasssse don' goooooo," Papyrus whined loudly. He wince afterward, pain flashing across his features. He swuitmed a bit under Sans, his knee coming up to brush at Sans's pubic symphysis. It was rough, making Sans wince a little. Nonetheless fire shot through his own bones. An itch to pull Papyrus closer nagged at him. No, no, no. He couldn't do such a thing. That was probably an accident to begin with.

"P-Papyrus," Sans started, shaking his head to stay focused. "I am just going to my room to get some medicine. I am not leaving you. Don't worry, I... I..."

Papyrus's eyes got hazier and hazier as he spoke. His sockets closed slowly until they were half-lidded. His grip loosened to just a small hold. He pawed at Sans's clothes lightly, begging. Sans's brow furrowed at the sudden change in behavior.

"Papyrus?" Sans asked. He didn't really get a response, just a whimper. "Papy?"

Papyrus gave a full body jerk under him, brushing against Sans's sensitive bones again. Sans had to bite back whatever noise that had tried to escape him. He pulled away a little more and noticed just how flushed Papyrus had gotten. His magic glowed brilliantly now, shining off his bones. His eyes easily caught where it was the brightest.

Papyrus's shorts were brighter than the rest of his body. He could sed the magic condensed inside his inlet. It was obvious what his brother had formed.

And Sans couldn't tear his eyes away from it. It was so bright but the shorts obscurred some of the coloring. He caught himself inching a hand down to pull those shorts the rest of the way off.

What was he doing? This was Papyrus! Thid was his _little brother_. He felt shame and guilt wash over him again. He loved his brother. Always had. He knew when his attraction started, but he had made sure to squash it whenever it reared it's head.

Despite the fact that they were brothers, it hadn't been hard to see that Papyrus was handsome. So very, very pretty... Seeing him like this didn't helo either. His magic was already coalescing in his inlet.

It was alright, though, right? Papyrus was asking for his help. Begging for it. He was just helping his brother. He was going to make him feel better.

Sans shot those thoughts down with a twenty-two. What the fuck was he thinking? Papyrus was drugged. Even if he did feel that way about Sans. Papyrus had no way of consenting while he was like this.

One long leg wrapped around Sans's hip and pulled him flush against Papyrus. Their clothes sexes lined up and Papyrus grinded into him.

"O-ohh shit..." Sans hissed, his head falling on Papyrus's clavicle. His internal conflict came to an abrupt halt as Papyrus's smell passed over him. He smelled faintly sweet and someehat smokey. More magic filled his mouth, condensing into a broad tongue.

He

He couldn't do this.

But, he could.

There was no telling what other chemical cocktail his brother had consumed tonight. He might not remember this at all. He may never know about Sans's feelings.

It's not right, though. It's fucked up. All of this is fucked up.

Even as he ground his cock into Papyrus, he felt shame and guilt and -

And so _fucking aroused_.

Angel forgive him.

Sans pressed his face further into Papyrus's exposed neck and just breathed in his natural smell. That sweet, smokey scent mixed with bone and something that was just Papyrus.

He was a weak, pathetic fool.

Sans adjusted his position to hover over Papyrus. He pressed a chaste kiss to his teeth, the only chaste thing that would happen tonight.

He was not worthy to be called a Royal Guardsman in training.

"Don't worry, Papy. I'll fix it. I'll make you feel so much better," Sans said, dropping his usual cherry falsetto for his more natural baritone voice.

He was not worthy of his brother's trust.

Papyrus whimpered and pawed at him again. Sans kissed him again, working his mouth open for a long, messy kiss he had been starving for. His brother could barely participate, only pushed back weakly at the small bit of stimulation.

The small, meek sounds escaping his brother only made his pants feel twice as tight. Wanting to hear more, his hands began to wander all over those pretty exposed bones. They were the true meaning of pearly. Not a single scratch on him, no scars, no marks, nothing. A side affect of having a single HP. Even Sans had his own scars from childhood accidents and guard training gone wrong.

And fuck wasn't Papy sensitive. He writhed with just about every single touch and graze against the inside of his ribs. He bucked against Sans every single time he got a little too close to his soul.

Wasn't that tempting. Sans had to stop himself. No, no, not this time. That would truely be crossing a line. If he were going to touch Papy's soul, Papyrus was going to be the one to ask him to do it.

Instead, he let his hands fondle the magic disks of his brother's spine. He dipped his finger into one and watched his brotger tense and shake under him, an absolute pornographic moan slipping from his teeth. Sans shuddered in turn, his cock throbbing for attention.

"Oh, Papyrus... the sounds you make are so sexy... So, so sexy... I need more."

Sans dipped one hand down to push his brother's shorts down further. His eyelights met plush, slick slips that called to him worse than a siren song. He gently touched those outer lips and moaned at the feeling. So soft, so wet, so very _inviting_.

He dipped a single finger inside him, slicling his finger up before he toyed with his brother's clit. His little bead was so swollen that it was poking out from it's hood. As soon as he touched it, Papyrus jerked. He didn't seem to know whether to push into Sans or pull away.

Sans dipped his finger back inside Papyrus, watching his reactions carefully. He watched his brother's face contort with plasure and the tiniest bit of overstimulation already. His face was burning with magic and tears were prickling his eyesockets. Nothing in his expression showed pain.

Getting impatient and excited, he inserted another finger. He worked them in and out of his brother smoothly, working him up making sure he was absolutely drenched when the time came.

This was so wrong.

That's why it felt so good. Sans pulled his fingers out and back leaned over his brother. He shoved his own pants down and to his knees. His dick stood at attention, leaking pre in his excitement. Sans squeezed the base of his cock with the hand he'd already wetted with Papyrus's fluids. It throbbed hard as he stroked it a few times only to slick himself up a little.

The cold draft of the house helped cool him down some, shoving down the excitemrnt for what he was about to do. He pulled Papyrus's legs apart and settled himself between them.

"I'll make all that pain go right away..." Blue murmured, his eyelights taking the shake of sharp hearts.

Sans wasn't a fool. He was _not_ his brother's first, just like his brother was not his first. But it didn't stop the feeling of pushing inside his brother for the first time from feeling special. Hell, it was euphoric in more ways than one. His little brother... His.

Once he was seated, he finally felt the sweat that had been building on his body travel down his bones. He let out a shakey sigh, fighting the urge to just spread Papyrus's legs further and fuck him into the floor. Instead, he kept pushing inside. Further and further, deeper until he finally hilted. Despite his size, Sans was not small. The fact that Papyrus took him without so much as a whimper of pain spike volumes to Sans of how they were made for each other. Papyrus was perfect, squeezing around him just right, like this was exactly what was supposed to happen. Like Papyrus's cunt was made for Sans and only Sans.

"Oh stars, Papyrus... Papy... you took me so well... so good..." Sans panted.

Sans didn't think it could get any better, until Papyrus's walls fluttered around him. A wave of heat passed over him, feeling almost like an orgasm itself. It nearly left Sans wrecked from the feeling. He recovered very quickly, but lost all control of his tongue.

"O-oohhh fuck yes..." Sans breathed. He started panting as sweet tingling waves went up his spine. At his cursing, his brother tightened around him again. "That's it, Papy... that's it... keep doing that. Fuck, you're so pretty like this."

Sans idly praised his brother, watching and feeling him react to each word. He would have to praise him more later just to see that pretty orange flush on his face. Papyrus was wiggling and writhing under him now more than before. Broken moans and sighs escaping him. His hips would jerk and push against his thrusts, protesting the slow pace Sans had set.

No. He was going to savor this. He was going to revel in this feeling of finally having his brother under him. His own hips jerked roughly in his excitement and Papyrus just _keened_.

Oh that sound... Sans was likely drooling. How unbecoming of him. Although, he was sure anyone would be affected just as bad as he was by Papyrus.

Lifting Papyrus's legs further apart, he laid down between them and onto Papyrus. His arms wrapped around Papyrus's body, idly toying with his ribs. His pace still slow and fluid as he rolled his hips into each thrust. Stars, Papyrus felt so good. So very, very good.

Shame he probably wouldn't remember Sans doing this to him. If he did, he would train his brother so well. But, Papyrus was under the influence. He didn't need to know Blue was taking advantage of him like this. So, he had to be gentle. If he wasn't, who knows what that knowledge would do to him.

Sans was helping him. He was helping get that aphrodisiac out of his system. He was taking care of him. Nice and slow. The person who drugged him wouldn't have been so nice.

"Yes... Yes... You're so pretty, Papy. So fucking gorgeous... ah.... hah.... ngh.. H-had my way, I would... I would ruin you. No one else can have you... oh... oh fuck..."

Sans sped up his thrust minutely. He could feel it. That hot coil was getting tighter. He pulled Papyrus in for a kiss, swallowing up all those sweet noises he was making. He could feel Papyrus tightening around him. Sans snuck a hand between then to help him along. He loved this. He loved his brother so much.

He pulled back Papy's clitoral hood and relentlessly teasted and touched his clit. Papyrus jerked under him, his walls fluttering around him.

"Look at you... You're doing so well. So well... My pretty Papy... My Papy. Mine. You're all mine... My pretty little brother..." Sans said. His thrusts became erratic as he felt those walls clamp down on him.

"A-Ahhhh!" Papyrus's body tensed up. A rush of hot liquid coated his cock. Sans groaned filthily against Papyrus's skull.

"Fuck yes! Papy... Papy... I-I'm gonna cum... I'm gonna... ngh... ah! Ahhh!" The tight coil snapped. Sans buried himself as far as he could into his brother. The head of his cock was grinding against the back of his brother's magic as his magic began to fill Papyrus.

"Come on... take it... take it all, Papyrus... You're such a good boy... My good boy..."

His brother sighed and then whined. His hips twtiched, wanting more contact. Sans held them still, pulling back to look at his handiwork. He hadn't cum so hard in such a long time. And yet he was nowhere finished with Papyrus. After all, it seemed like Papyrus was still very much under the influence of those drugs.

Blue pulled out and relished the sight of his cum running out if Papyrus's swollen cunt. He licked his teeth. It would be a shame if Papyrus woke up dirty...

Spreading his brother's legs again, he dove between them to have a taste.

* * *

"Ugh... I feel like shit..." Papyrus groaned from the couch the next day.

"You overdid it again at the bar, Papy. I keep telling you to be more careful. Do I need to go have a word with Muffet about this?"

"Nah, bro. It's just a small hangover. I'll get over it. What's killing me is my spine though," Papyrus said. "It feels like I got..." Papyrus went silent, his fave flushing a bit.

"Like what Pappy?" Sans asked, sincerely curious. He tilted his head to the side innocently as he watched his brother think.

"L-like Alphys used me as her personal boulder stand," he stuttered out. "But, hey, I'm used to being stoned all the time."

Sans threw down his dishwrag with a frustrsted sigh that condradicted his smile.

"That was a stretch and you know it!" he replied, playfully exasperated.

"Yeah, I guess you're right," Papyrus conceded.

"Of course I am! I am magnificent after all!"

"Yep... you sure are the coolest."

* * *

Papyrus stared at Sans's back as he washed the dishes. He had almost let it slip that he felt like he got railed into the carpet. He flushed as little snippets of the night lingered in his skull.

He needed to talk to Muffet about that little pill she slipped him again. Maybe he could get his hands on some more....

**Notes for the Chapter:**

> Pretty, pretty please don't judge me for the spelling mistakes and typos that may be in this. I typed it out all on my phone.
> 
> I hope you guys enjoyed this chapter. Thank you for reading, please let me know what you think with a comment!


	3. Swapfell Bros with Creep Sans

**Summary for the Chapter:**

> Papyrus just worked up the confidence to talk to his advisor.
> 
> (Sans and Papyrus are not related in this.)

**Notes for the Chapter:**

> This was a little idea that rolled into something i really liked. I hope you guys enjoy reading this as much as I did writing it.
> 
> Please have mercy on me. ALL of this was typed on my phone. Please ignore the typos i missed while editing.
> 
> Warnings: Rape, Non-Con, Drugged Drinks, College AU, Teacher/Student, Possesive Sans, Creep Sans, Optimistic Papyrus, Nervous Papyrus.

Papyrus hesitated, his fist shaking a little where he held it in the air. He needed to go ahead and talk to him. He needed to get it out of the way.

No, Pap, he's not gonna yell at you or be angry at you. He will understand. That is how this always goes. It will be fine. Take a deep breath. You've got this.

He raised his fist to knock only to freeze as the door opened slowly. He came face to face with the person he was so scared of meeting. Upon seeing him there, the other jumped.

"Oh, god. Papyrus, you scared me," the other said, adjusting his glasses. Those striking purple eyelights snapped onto him with a firm stare. Professor Sans Serif was the skeleton in front of him. He taught many literature classes ranging from ancient to modern day.

"Sorry," Papyrus replied lamely.

"I was just on my way to dinner. What brings you here so late? Did you want to talk about something?"

Papyrus flushed a little and nodded. He hadn't realized how late it was. He just knew that Dr. Serif would be in his office. He was a nice guy most of the time, but not one anyone should piss off. And pissing this guy off was what Papyrus was afraid of.

Dr. Serif stepped back and motioned for the other to enter.

"Come on in. I'll make some tea," Dr. Serif said, his expression held some worry. Papyrus relaxed on fractionally.

Papyrus stepped into the office feeling very underdressed. He wore his favorite hoody that made him feel safe during uncomfortable conversations and interactions, but it wasn't somethin he felt he should wear in this room. It was awe-inspiring. Books of all kinds adornef the walls in massive bookshelves. While it was a small office, it seemed so much bigger than it had a right to with how clean Dr. Serif kept it. A loveseat sat on the backwall that Papyrus took a seat on.

It looked so nice and a deviant like him just didn't fit in here.

Dr. Serif stepped by and went to his desk. He pulled his coffee maker off the bookshelf and pulled out a couple of bags of spiced tea. Papyrus flushed when he noticed his favorite cinnamon black tea now joined the collection he had. Dr. Serif himself was partial to normal black tea.

"So, what brings you here so late? If you're worried about your paper, don't be. I went over them all tonight and yours was excellent."

Papyrus flushed again at the praise. He hadn't thought his paper was that good. He wrote it an hour before class after all. But, that wasn't why he was here. He was here for an entirely different reason.

"That's nice to know, Dr. Serif, but -"

"Call me Sans, please," Dr. Serif reminded. He always reminded his students to call him that and emphasized it. He poured hot water into their cups and motioned for Papyrus to continue.

" - ... Sans, I... I came here to ask for my academic folder," Papyrus said.

Sans paused. He didn't turn around though. He kept his back to Papyrus as he fixed their tea.

"You're changing your major, then?"

"Yes, sir," Papyrus replied politely and with as much professionalism he could.

"That is a shame. I had hoped you would stay with the arts since your papers are simply brilliant," Sans sighed. Papyrus could feel his disappointment and fought down the feelings of guilt that began to form. "What are you going to?"

"Engineering," he answered.

"Ah. I see," Sans said without much emotion in his voice. Then he turned towards Papyrus with a smile. "They will be lucky to have you there. How many sugars?"

"Three please," Papyrus said, returning the smile. That had... surprisingly went better than he thought. After another minute of stiring, Sans handed the tea to Papyrus.

"It's a different brand of sugar than my normal, so please don't be surprised if it tastes a little funny," Sans warned. "That is the last time I send Blue to get more sugar for me."

Blue was Sans's 'nicer' brother. He was Sans's twin who was cheerful and uppity. From Papyrus's own experience, Blue was the type of guy to insult you with a smile and a giggle. He warily took a sip of his drink and sighed a little. It was much sweeter than usual with that hint of bitterness from the cinnamon. Papyrus was more than satisfied.

They started conversing about Papyrus's new plans and aspirations for this new field of study. They discussed pros and cons of the field, while a bit intimidating, it didn't get Papyrus down. He knew he could do it. He had been passing his current classes with flying colors. Sans was more than helpful when it came to giving advice, even go as for as requesting he take up certain professor as his advisor. He promised to help Papyrus in any way he could.

It was a wonderful talk and before he knew it, it was already nearing one in the morning.

Wait. No...

It couldn't be that late. It was eleven only an hour ago.

No, no. That wasn't right. The clock was reading 2 am. Or was that a five. When had he gotten so dizzy?

A wave of woozyness hit him like a bat to the skull. He swayed in his seat a little. His hands stopped cooperating. His empty cup fell to the floor in a thudding clatter.

"Papyrus? Are you alright?" Sans asked.

"Y-yes. Well... n-no actually. I feel... dizz... dizzy..." The world was spinning. The edges of his vision blackened. He couldn't concentrate. Everything in his head was telling him to let go and sleep then and there. He fought it.

"Not... not okay," he forced out, his words slurring horribly. "Call... am.... bu...lance.."

He blacked out.

* * *

He felt warm. Groggy and very, very, warm. He was hot. Sweating. What happened? He couldn't quite remember. He felt hot jolts of warmth and pleasure run through him, making him moan softly. He head wouldn't clear. There was someone above him, on him. Papyrus felt his soul stop for a moment. The person was inside him, pushing in at a gentle and loving pace.

He felt horribly disconnected to it, but each thrust brought him back closer to what was happening.

It felt like a wet dream but not. His magic tightened into a knot in his abdomin. He felt nauseated. There was no reason though. This was just a dream. Right? Right. Papyrus didn't have the mental capacity to even begin wondering what he would do if it wasn't a dream.

_(He didn't remember falling asleep on Dr. Serif's couch.)_

He peeked his eyes open a little. Everything was blurry. It looked like he was still in Dr. Serif's office but the lights were off. His legs were wide open, wrapped snugly around someone's hips. This position was nothing new in his dreams and fantasies and neither was this place. He would never admit that he had fantasies of his teacher fucking him into his immaculate desk and making a mess of things. He would be mortified if anyone found out. The thought alone made him tense up in embarassment.

"Oh fuck! Papyrus... you're so perfect, fucking hell," said the person above him as they fucked into him harder. A loud whine escaped him from the stimulation. Stars, that had felt amazing. He looked up to see who his lover was for this dream. Of course it was Dr. Serif. He could barely make out those sharp teeth and purple eyelights. His purple glasses were missing, but it was him.

"Keep squeezing me... just like that," he went on, even kissing his sternum. He was so short... Papyrus snorted a little. Dr. Serif - no - Sans jolted back a little, apparently startled. It jostled his member inside of Papyrus, hitting his g-spot easily. Stars, his dream was probably exaggerating Sans's size but he didn't care. His back arched as much as it could on the tiny couch. He let out a broken moan and pushed back against Sans needily. This was his dream, fuck his inhibitions.

Depsite his wiggling, Sans didn't move. He stood still as a statue, looking down at Papyrus with an expression he couldn't really see. The dream was way too fuzzy. 

"You... Do you want this?" Sans asked with what sounded like bewilderment.

"Wha...?" Great response there, Pap. Good job. Nailed it. No, try again, you ineloquent fuck. "W-well, yeah..." he said. It's pretty obvious. He was making it pretty well known that he wanted it but trying to rock back into Sans's dick. Wait. Was this gonna be one of those damned dreams where he gets fucking denied because he likes it. Fucking hell, shoot him now or kick him awake, he was gonna murder someone when he woke up if that was the case.

_(Won't you wake up in his office though? Why hasn't he woken you yet if you fell asleep?)_

The grip on his hips tightened as Sans's eyelights bored into him. Fuck it was gonna be one of those dreams. Goddamn it.

"Tell me why."

Papyrus shuddered as how deep those voice got. He didn't think he ever heard it get like that before. It sent hot chills down his spine, making his toes curl and his cunt clench.

"Wh-What?" Papyrus gasped out, loving how the words were said but not quite comprehending them. Stars, if only Sans talked to him like that all the time. Suddenly, Sans was pulling out of him, going at a snail's pace doing it. "What? No, wait..."

Papyrus attempted to reach down and pull him back. His coordination was nonexistent. He just ended up pawing at Sans's arms. Sans was smirking, grinning down at him with a sharp smirk.

"Tell me, Papyrus. Tell me why you want this."

Those words slowly sank through his mind fog. Why did he want this? That was weird to ask. He should know since this was just a dream. Then again, this was a bitch of a dream. Fuck it. He'll play along. He was horny as fuck and needed a good orgasm.

_(You're not thinking clearly. You're not where you think you are.)_

"'Cause i's you," Papyrus replied, his words still slurring. "'Cause you feel so... good in me... please... please move..."

The other's eyelights flickered. He couldn't tell what shape they took. His head fell back against the couch again as the other thrust back into him. Teeth scraped at his ribs and clawed fingers pricked at his bones. No marks though, no matter how badly he wanted them.

"You're a gem," Sans breathed gently. Papyrus whimpered at the praise. "You have so perfect, so smart, so beautiful."

Papyrus gasped, heat flooding his face. Oh dear stars, this was good. This was fantastic. Please, please, please don't stop!

"I won't, precious. I'm gonna make sure you get yours," Sans purred. Suddenly, his hands were everywhere, gone from his hips to his spine to fondle it, to his thighs to spread his legs wider. Papyrus happily obliged, spreading them wide. Sans cursed, whatever control he was using slipped and he thrust hard into Papyrus who yelped and then shook as pleasure flooded over the pain. He wanted more. He needed more.

Sans was close too. His pace was stuttering, even as he went faster. He wasn't rough, depsite how badly Papyrus wanted him to be. One of his hands went to Papyrus's clit, pressing and rolling it, pinching it. Papyrus jerked hard. His walls were starting to flutter. He was close. So, so close.

Thr endorphins were making him dizzier. He was almost there, almost...

Sans thrust in one last time and stilled with a moan that sent another shiver through Papyrus. He didn't feel any warmth flood him, as expected. This was a damned dream and of course he would be left unsatisfied. He whined as Sans pulled out of him. Stars, that felt so real.

_(Too real. It had to be.)_

Sans was panting softly. He had the thinnest sheen of sweat on his bones. Papyrus felt terribly cold when he pulled away. Whining louder, he reached for Sans. His professor just grinned, all teeth and predatory. He went down Papyrus's body slowly, crawling until he was eye level with his pussy.

"I promised that I would take care of you," Sans growled. Then his tongue was on him and Papyrus couldn't remember much of anything else.

* * *

He woke up with a violent jolt, nearly falling off whatever he was laying on. The couch. He was still on Dr. Serif's couch. What the hell?

Dr. Serif was sitting at his desk, reading over student papers and making notes. Papyrus moved to sit up and grabbed his skull. It hurt. Migraine. Shit.

A blanket fell off his lap and onto the floor. It suddenly felt way too cold in here. Oh. The window was open. No wonder.

Shit! His magic was still summoned. His pussy felt swollen and puffy when he shifted in his seat. The faint smell of his arousal wafted up to him through his pants. Shit, shit, shit! He had a fucking wet dream about his professor in his professor's fucking office.

His skull blazed with light at the thought. He hoped that Sans - no, you dumbass! - Dr. Serif hadn't and wouldn't notice his smell. Oh fuck, that wouldn't matter if the man heard him moaning like a slut in his sleep.

Dr. Serif turned around in his chair and stopped.

"Oh. You're awake. It was about time. You should be getting back to your dormroom soon," Dr. Serif said. "You should take better cate of yourself. You passed out while he were talking. Nothing seemed to be wrong so I just let you sleep."

"Oh. Um, sorry... i didn't... i..." Papyrus was at a loss of words. He hadn't felt particularly tired earlier. He shuddered at the thought that he would need to go see a doctor. Passing out like that was not okay. He remembered drinking tea with his professor and... and...

There was a gap in his memory and then he had that dream and then he woke up.

There was a gap in his memory... that was mildly worrying. Then again, he trusted Dr. Serif. He had no reason to question him.

_(Liar. There are plenty of reasons to question him. You just don't want to.)_

"I... guess I didn't know how tired I was."

Unperturbed by his stuttering and nervousness, Sans said nonchalantly, "Well, we did talk for quite a long while. I did take a small nap myself. It's almost six in the morning. It is a good thing today is Saturday and you don't have classes."

"What?!" Papyrus squeaked out, scrambling for his phone. He looked around the room and found it on the floor. It must have slipped out at some point. Clicking the side button, he checked the time.

Fuck it _was_ almost six in the morning. He needed to get back to his dorm. He needed to sleep in an actual bed. He felt like shit. That didn't matter, he needed a shower and his toys. He might have to hit Red up later for a quicky.

Standing up, he got that uncomfortable feeling like all his clothes were askew. He quickly readjusted everything and straightened himself. He turned to his professor one last time, right as he was throwing some poor sod's paper in the trash. Poor guy.

"Thank you for letting me stay here. I am sorry i passed out like that," Papyrus said, barely remembering to keep a good distance so the other wouldn't smell him.

"It wasn't a problem. I quite enjoyed the quiet company," Dr. Serif replied and adjusted his glasses.

"Oh. Well... uh... thank you. Bye," Papyrus said, awkward and really wanting to get out of there as soon as possible. He rushed out the door and was halfway out the door when he heard Dr. Serif call for him. His professor stood up from his desk and pulled a folder out of his stack of papers.

"You nearly forgot your file. Administration will try to assign you an advisor but you can ask for one yourself. Dr. Comic would love to have you in his classes. Trust me. And -"

Papyrus was barely listening. Dr. Serif was in his personal space, only a foot and a half away. He took the folder gently holding it an inch from his chest as he sweated nervously.

Suddenly Dr. Serif stopped talking and his face scrunched in confusion. He could hear the other take a big wiff of air and then another.

"Papyrus?"

Shit. Fuck. He could smell him. He could smell his fucking arousal. Goddamn it. He took a step away from his professor, hoping he did so subtly.

"Is that cologne you're wearing? It smells nice. What kind is it?" Dr. Serif asked, leaning in a little closer.

What? He wasn't wearing -

_LITTLE BLESSINGS JUST ROLL WITH IT!_

"Uh - da - um, i-it's that Axe spray. That Axe Pheonix cologne," Papyrus lied, knowing Dr. Serif hated that shit.

As expected, his professor's face turned to confusion and then scrunched up in distaste. Dr. Serif took a step back, putting a good amount of space between them.

"Of course. Lack of sleep must be affecting my nose. Well, go on and go back to your dorm. Stop by the cafeteria and grab a muffin though. Eat something, take care of yourself."

"Will do. Bye!"

Papyrus fled.

* * *

Sans stood in the doorway to his office, watching Papyrus go.

"Smart as hell. Not a very convincing liar," Sans muttered to himself. He walked back into his office and pulled the paper he tossed into the trash back out. It had been Papyrus's paper. Underneath it, in the bin, was a used condom. He read over the paper again with delight in his eyes.

"Oh, you will be mine, precious. You will be _mine_."

**Notes for the Chapter:**

> I hope you guys enjoyed this chapter! Please let me know what you think with a comment! I thrive on comments!


	4. Classic Fontcest

**Summary for the Chapter:**

> Sans goes overboard.

**Notes for the Chapter:**

> This is acrually a continuation fo one of my previous fics. I believe it was part of the Extremely Naughty Tumblr Fics. I didn't actually go check, but redtomatofan mentioned the bonecarving stuff and I wanted to touch on it again. So here it is. I hope you guys enjoy!
> 
> Warnings: Non-Con. Creep Sans, Posessive Sans, Blood, Bone carving, Sadism/Masochism, Knife Play, Pain play, Bondage, Mind-Break.

Sans went overboard. He knew he did, yet he really couldn't care less. Papyrus's hands were tied together above his head, to the little rail at the headboard of his racecar bed. His bones rattled softly, still stinging in pain that slowly ebbed away.

Just off to their side was a knife gleeming maliciously back at him in the light their magic cast. The tip was stained red and had flecks of dust on it. His dust. Papyrus let out another choked gasp as Sans's cock hit a spot deeper inside him.

"fuck, you're so pretty... so beautiful like this, Paps..." Sans groaned just a little louder than the creeking of the bed. A vicious heat curled inside Papyrus, unwanted arousal from the praise. He wasn't pretty. He wasn't by any means, but the way Sans said it almost made him believe it.

He jerked and let out a strangled moan through his gag, his own underwear, as Sans licked along his bleeding ribs. Each one was cut, carved and marked in some way, whether it was bitemark, clawmark, or Sans's name carved into him.

Each mark leaked lightly except for his sacrum. The cuts on his sacrum had leaked liberally enough to stain the sheets of the bed, his brother's hands, and various other spots on his own person.

It had just gotten to where it clotted.

He shuddered hard when Sans dug his thumb into the cuts on his spine. Sans paused, stopping completely. Papyrus barely paid him any mind. He had given up on trying to stop Sans. His bother was likely going to try something else now, so Papyrus decided to focus on the warm cotton that seemed to seep into his bones.

Sans flicked his thumb again which seemed to ignite all that cotton for a brief moment, ripping a gasp from Papyrus. The feeling settled again and Papyrus let out a small groan.

"do you... do you actually like that, Paps?"

It took several minutes for Papyrus's mind to catch back up. That had sounded so strange, like a legitimate, concerned question from his deranged brother. Then the words sunk in and Papyrus felt a whole new wave of shame wash over him.

He had liked it. He had liked it when his brother hurt him just then. Sans sat back and shakily took Papyrus's gag out of his mouth. It was soaked with saliva.

"Paps..." Sans whispered softly. His hand caressed Papyrus's cheekbone, right against the cut there. The taller skeleton quivered and leaned into the touch.

"S.... sans...." His voice came out in a raspy, barely there whisper.

"O-oh fucking hell..." Sans shuddered hard. His hips started moving again, slower than before. The drag of Sans's magic in and out of him sent pleasant shivers through him. He wanted to feel sick that those sparks of pleasure had him twitching, wanting more.

"Fuck, fuck, fuck, ok... shit," Sans pulled out quickly. He pulled away and scooted down while he rambled. "goddamn, you're so much better than i thought, Paps. you're so fucking perfect. i should treat you better..."

He whispered that last sentence against Papyrus's exposed sex. The next thing he knew he felt soft, slick magic sliding against it enthusiastically. The feeling had him writhing on the bed. He tugged on his restraints, clawed at his headboard, twisted and turned while his traitorous legs spread themselves wider. Sans's tongue speared into him, tasting everything inside his sex and then pulling back to suck on his clit.

"Oh, oh fuck! Sans! Sans!" Papyrus felt horrible for giving into to this. It was so fucking disgusting and wrong and horrible, yet Sans made it feel so good now. Soon all he could think about was how good it felt.

"that's right, Paps," Sans groaned against him. "say my name. scream for me some more. let me hear how good you feel."

Papyrus was powerless to do much else. Sans was an expert with his mouth. He brought Papyrus close to the brink and held him there for a long time. Well, it felt like it at least. It was probably only ten minutes. Sans would tongue fuck him for a little while, then pull back to breathe against it while he dug his fingers into some of his cuts.

He could only take so much before he broke...

"Please..." Papyrus sniffled. Sans pulled back with a harsh frown on his face. He'd pissed Sans off earlier in the night when he begged him to stop cutting him. Sans probably thought he was doing it again.

"Please, Sans... please... I need more..." he whispered, his voice breaking here and there.

Sans's frown disappeared quickly, as well as the anger in his eyes. It was replaced with an almost worshiping gaze, filled with gentle reverence and unparalleled delight.

"anything... anything for you, bro," Sans replied. His own eyelights were hazy and dilated. There was so much love in his eyes, despite how warped it was.

Sans lined himself back up and pushed inside slowly. Papyrus could feel every inch as he pushed inside. It baffled him how Sans could reach places inside him that Papyrus had been unable to reach with his long fingers. He pushed against hypersensitive spots that had sung out in pleasure once they were touched again. Papyrus tipped his head back as he was hit with almost too much sensory input.

He let out a loud moan as Sans hilted himself and rolled his hips slowly. His brother groaned above him, sending hot bolts up his spine. He should be hating this. He should be hating Sans for this. But, stars it felt too good now.

Without Papyrus needing to ask, Sans moved slowly. He seemed to be savoring the feeling now, not that Papyrus blamed him. It felt so much better to go slow. It didn't hurt him nearly as bad as that fast pace did. But, pain was still there. He ached so bad that the gentleness stung almost as bad as the knife had.

Sans draped himself over Papyrus's body. He kissed his cheekbone and his neck, licking at the cuts that had stopped bleeding. The pain had him twitching pleasantly.

"stars, you're perfect. you're the best person out there, Paps. you're so amazing and cool," Sans murmured. His pace sped up just a bit as he buried his face deeper into Papyrus's cervicle vertebrae. He sucked at the bones and scraped his teeth against them hard. Papyrus shuddered, his own moans becoming shakey. He tilted his head aside to allow Sans more access.

Sans took the opportunity to greedily bite into those bones. His phalanges dug into Papyrus's sacrum, sending a whole new wave of pain and pleasure through him, building upon the last and pushing him closer. He need it. He needed to come so badly.

Something was wrong. Something was missing. Papyrus couldn't put his finger on it even if his hands weren't bound.

Sans speed up his pace, grunting louder. The studder in speed told Papyrus that Sans was close. That this would be over soon. His mind hadn't quite caught up with the idea that Sans would do this again and again. He was just looking forward to finishing.

Then a cold familiar scrape of metal against bone sounded in the room. Papyrus's soul dropped. The scraping had come from his ribcage. Sans had the knife in his ribcage, it was near his soul. Stars, Sans was actually going to kill him.

"shoosh, shoosh, shoosh, shhhhhooosh. it's okay. it's alright, Paps. i'm not gonna hurt ya. i love you too much to do that."

_Too late..._ Papyrus thought bitterly, even as Sans's pace dragged to a crawl again. Fuck, his brother knew just how to torture someone.

"I would never want to hurt you," Sans continued. "Not unless you want me to."

That cold steel crept closer to his soul. Papyrus suppressed what would have been a violent jerk at the feel of that frigid metal touching his soul. It burned against him. It didn't press into his soul, just glided against it. Tension built in Papyrus's body as he forced himself to stay still. Holding his breath, all he could do was gaze at his ribs in fear. He couldn't see what was happening. He couldn't see it through his sternum but stars he felt it.

Just the gentlest of pricks into the tip of his soul. But the intent sent waves of alternating pain and pleasure through him. The clang of metal against bone resounded across the whole room as Sans snatched the knife out of Papyrus's ribs and across his spine in a long strike.

His HP was normal. No damage taken. Just agony and ecstasy. Papyrus's vision went white as his whole body seemed to snap with that singular movement. He screamed as fluid gushed from his cunt, belong to both him and his brother. Sans moaned loudly into Papyrus's ribs, clearly savoring the feeling of his orgasm and Papyrus's walls fluttering around him.

As he came down, the tension left his bones in incriments. With each second, his body felt heavier and relaxed a bit more. He could feel healing magic in his ribcage, against his soul. The intent was so loving and warm, his head felt clouded and foggy.

Sans pulled away, still very much seated inside him. He rolled his hips a little, waking Papyrus from his daze. He gently grasped Papyrus's mandible and pulled Papyrus to meet his gaze.

"now who do you belong to, Paps?" Sans asked.

His brother's gentle movements turned into rocking. The action made his scabs on his sacrum catch and rip off. Sans's name would be a permanent scar there.

"You, brother..." Papyrus answered, defeated. "I belong to you."

**Notes for the Chapter:**

> Hope you guys enjoyed this chapter. Please let me know what you think with a comment!

**Author's Note:**

> Please, please, please forgive any mistakes you see in this. I typed it up on my phone because I don't have internet otherwise. I hope you guys enjoyed the chapter and thank you for reading!


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